Sam Querrey admits that he lost some motivation in 2013, partly because he and his fiancée, Emily McPherson, broke up during the summer.
"Mentally I don't think I was all there,” he told USA Today about his second-round loss to Adrian Mannarino at the U.S. Open. "I'm no longer engaged. I'll tell you that."
Querrey reached a career high No. 17 in 2011, but has fallen to No. 46. He has only won one singles title since 2010, in Los Angeles in 2012.
In 2013, he reached the fourth round of Indian Wells and Miami but then struggled. He did reach the third round of Roland Garros, where he pushed Gilles Simon to five sets.
"I wasn't really enjoying it as much as I should have. I got into a little rut," Querrey said. "I'm not exactly sure what the right word is. Just kind of over it for a little bit."
After suffering an abdominal injury at the Shanghai Masters in October, the 26-year-old American shut his season down. But he is optimistic about his 2014 season, which will begin in Brisbane on Sunday.
"If I fine-tune everything just a little bit, not even a lot, I can jump into the top 15," he said.